I was just reading the Tech Section on Ranger engines, in particular the 3.0. The author explains how to install a 60mm Escape throttle body.
https://www.therangerstation.com/tech/60mm-3-0l-escape-throttle-body-on-3-0l-ranger-intake.
The article is well written and the directions are pretty clear.
I'm just a little skeptical. There is no mention of performance data. Can we really expect better acceleration or improved mileage? Did the Ford engineers make a mistake? Why did they put a 52 in the Ranger and a 60mm in the Escape?
Have any of you actually done this? How did it work?
Ford put a larger throttle body on the 3.0
Duratec found in the Escape than the 3.0
Vulcan in the Ranger because it rev'd higher/made more power.
3.0 Duratec 240 hp @ 6,550 rpm (4 valve/cylinder, DOHC)
3.0 Vulcan 140 hp @ 4,800 rpm (2 valve/cylinder, OHV)
The Duratec is basically reving 1/3 faster than the Vulcan, so the throttle body needs to flow 1/3 more. 60mm throttle body is more/less 1/3 greater in area than the 52mm. (The little extra power the Duratec makes proportionately is due to aluminium heads allowing higher compression)
Anything less than 5% is within error of the dynamometer. (Changes in temperature/humidity/air pressure make more difference).
If the tb is too big, driveability suffers. <- great statement
With the cam/heads/intake/etc set up to make best power at ~5k rpms, the intake valves need to open before top dead center (TDC) and close after bottom dead center (BDC) as the valves and the air in the intake manifold have inertia.
However, at just 1,500 rpm (e.g. cruise), opening the valve(s) before TDC/leaving open after BDC results in air being pushed out of the cylinder i.e. less than 100% filling.
A smaller throttle body ensures there is flow in the correct direct through the throttle body and into intake keeping the cylinder closer to full.
So, the engineers at Ford compromised the throttle body between better response a "normal" rpm over maximum power. Some of the factory 'imperfections' are designed to be there to create turbulence - which helps prevent detonation (turbulence ensures proper mixing of air & fuel).
Now, the hot rodders, replace the compromised throttle body with a maximized one and get better top end numbers. But give up power down low/driveability. They also set air fuel ratios closer to ideal (even a little lean of ideal) which again is great for a single dyno pull (or 1/4 mile) but burns exhaust components on a long climb pulling a trailer in your truck.
Note: Maximum power at wide open throttle on a dynamometer does
not translate into usable power at part throttle on the street.
Engineering is taking the theoretical from the scientists and translating it with the desired compromises into what the end user wants. Ford's engineers compromised on what the average user* wanted; might not be what the enthusiast wants...
Average user includes the government regulators.